Bifunctional Pd‑O_x Center at the Liquid–Solid–Gas Triphase Interface for H₂O₂ Photosynthesis

The coupling of H₂O and O₂ by solar energy is regarded as the Holy Grail reaction for a manufacturing route of H₂O₂; however, its efficiency has suffered from low O₂ solubility in aqueous solution and difficult-to-inhibit side reactions. Herein, a liquid–solid–gas triphase system has been designed to directly utilize abundant atmospheric O₂ for H₂O₂ photosynthesis, the most important of which is the superhydrophobic photocatalyst of amino-containing ligands combined with Pd, loaded on BiVO₄ (Pd/A/BiVO₄). This relatively separated catalyst and product system successfully avoids the decomposition of produced H₂O₂ and contributes to the accumulation of a high-concentration H₂O₂ solution. The enrichment of O₂ and the kinetics of carriers and reaction intermediates are tunable via the interaction between Pd and amino groups, which promotes the photosynthetic yield of H₂O₂ to 805.9 μmol g^–1 h^–1 in pure water under visible illumination. During the reaction, O₂ is not only converted into H₂O₂ as a reactant but also participates in the construction of Pd-O_x sites as a dynamic catalyst. Also, the Pd-O_x intermediate is identified as a catalytic and photoelectronic dual center. This research opens up an intriguing avenue for designing the H₂O₂ photosynthesis system.